Did this by waiting for a batch of MAM messages to arrive before
prepending them to the buffer. Also limited the number of messages
to fetch to 10 so that the user gets more frequent updates.
We now dont get the log files from the text files via chat_log_get_previous() anymore.
We use the sql backend via log_database_get_previous_chat().
So far it just has the same behaviour like chat_log_get_previous(),
except that in _chatwin_history() we don't pass the sender to
win_print_history() which should be fixed in a commit soon.
And log_database_get_previous_chat() can later easily be expanded to fix
https://github.com/profanity-im/profanity/issues/205.
I plan to save all messages in an SQLite db.
For retrieving information it's nicer than having it in a text file.
We will have more info in there and easier to parse it.
This will also be good for later MAM
(https://github.com/profanity-im/profanity/issues/660).
Regular text files will still be an option for users so that they can
easily grep them and do whatever they like.
Internally Profanity will only use the SQLite db.
